August 2008

 

OPHTHALMOLOGY NEWS

 

Pinpointing pink eye


by Vanessa Caceres EyeWorld Contributing Editor 

   

Test helps make diagnosis easier

The Adeno Detector helps screen for pink eye Source: Rapid Pathogen Screening

A patient walks into your office with a garden-variety red, watery eye—you suspect viral conjunctivitis, but it could be bacterial conjunctivitis, allergies, or something else.

How do you differentiate what the problem is? A new test from Rapid Pathogen Screening (RPS, Sarasota, Fla.) is helping ophthalmologists, optometrists, pediatricians, and emergency room and family physicians determine who has viral conjunctivitis—so-called “pink eye”—and who doesn’t.

The RPS Adeno Detector has been on the market for a little over a year and half and can detect the 51 serotypes of adenovirus, said RPS medical director Robert Sambursky, M.D. A study published in Ophthalmology in 2006 found that the test has an 89% sensitivity and 94% specificity compared with the polymerase chain reaction (PCR), another test used to diagnose pink eye.

A PCR test isn’t always easily accessible to doctors in private practice who need to make a relatively quick determination of pink eye. Viral cell culture is another way to help diagnose the patient’s condition, but the results take awhile to obtain.

At the beginning of this year, a reimbursement code was established for the use of the Adeno Detector.

How it works

The Adeno Detector is an immunoassay test that looks and works similarly to a pregnancy test, Dr. Sambursky said. The test has a CLIA waiver, so a doctor, nurse, or technician can administer it. A sample is obtained by dabbing the sample collector on the lower eyelid along the palpebral conjunctiva six to eight times. “The sample collector is dipped in solution for 10 seconds, and 10 minutes later, there’s a result,” Dr. Sambursky said. One line indicates a negative reaction; two lines mean the patient has tested positive for some form of adenovirus, or pink eye.

The test is easy and helps doctors differentiate pink eye from other conditions, Dr. Sambursky said. “The problem is that many conditions present the same way, with a red eye, tearing, and itching. The signs and symptoms are similar, so it’s hard to differentiate them,” he said.

Physicians who use the Adeno Detector agree that assisting with a differential diagnosis is how the test works best. “I have found it helpful in cases where the diagnosis is unclear and I’m considering the use of topical corticosteroids,” said David B. Glasser, M.D., assistant professor of ophthalmology, Johns Hopkins University School of Medicine, Baltimore. “For example, in patients with severe follicular conjunctivitis and a positive pre-auricular node, a positive result can be reassuring that herpes simplex is not the etiology.” However, a positive result does not necessarily mean a patient does not have herpes simplex virus (HSV), Dr. Glasser added.

Richard S. Davidson, M.D., assistant professor, Cornea, External Disease, and Refractive Surgery, Rocky Mountain Lions Eye Institute, University of Colorado School of Medicine, Aurora, also finds it helpful that technicians can perform the test.

The test results come in handy to determine a patient’s best course of treatment, such as staying home for a few days to avoid the spread of the contagious condition or avoiding the use of antibiotics if it’s not a bacterial case.

“It can help differentiate tough cases but more importantly, it helps me advise patients,” said William B. Trattler, M.D., director, Cornea, Center for Excellence in Eye Care, Miami, “If the test is positive, you don’t have to put the patient on antibiotics they may not need,” Dr. Sambursky said. By honing in on the patient’s exact problem, Dr. Sambursky said that physicians help curtail future problems from long-term conjunctivitis, such as light sensitivity, decreased vision, chronic dry eye, foreign-body sensation, and scarring.

Consistent use of the test also could help lead to an annual cost savings of $500 million that is currently associated with conjunctivitis, a figure that’s slated for publication in an upcoming issue of the American Journal of Medical Sciences, Dr. Sambursky said.

Making the test better

The Adeno Detector is undergoing some modifications that are slated for introduction in early 2009, Dr. Sambursky said.

Hopefully, these modifications will include clearer results, Dr. Trattler said. For example, sometimes the positive test line is faint so it’s hard to tell the actual result.

The test would also be more useful if there was an accompanying test to help clinicians diagnose HSV, Dr. Glasser said.

In fact, such a test is undergoing clinical trials at RPS right now, Dr. Sambursky said.

“An HSV test would be remarkable,” said Dr. Trattler, who is an investigator with the current HSV trial. “It’s nice to choose cases where we’re not sure if it’s HSV or something else. Having the ability to determine if it’s HSV is critical.” The company also has a similar non-specific test in development for ocular allergies, Dr. Sambursky said. It will aim to help pinpoint mild to moderate allergy, and clinicians can use it before as well as after allergy treatment to see how much the treatment has alleviated the patient’s signs and symptoms.

Ideas are also underway for tests for dry eye and chlamydia, Dr. Sambursky said.

Editors’ note: Dr. Sambursky is an employee of Rapid Pathogen Screening (Sarasota, Fla.). Drs. Glasser, Davidson, and Trattler have no financial interests related to their comments.

Contact Information

Davidson: 720-848-2504, richard.davidson@uchsc.edu

Glasser: 410-964-4690, dbg@comcast.net

Sambursky: 941-556-1855, sambursky@rps-tests.com

Trattler: 305-598-2020, wtrattler@gmail.com

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